cf-ref-proxy.js

const reverseProxyBase = {
  acgnx: "share.acgnx.se",
  acgrip: "acg.rip",
  bangumi: "bangumi.moe",
  dmhy: "share.dmhy.org",
  mikan: "mikanani.me",
  miobt: "miobt.com",
  nyaa: "nyaa.si",
  nyaa_sukebei: "sukebei.nyaa.si"
}

function noSuchWebsite(name) {
  let available = ""
  for (let key in reverseProxyBase){
    available += key + ": " + reverseProxyBase[key] + "\r\n"
  }
  if(!name) name = "<empty>"
  return new Response(`No website matching name "${name}"\r\n\r\nAvailable:\r\n\r\n${available}`)
}

function escapeRegExp(string) {
  return string.replace(/[.*+?^${}()|[\]\\]/g, '\\$&'); // $& means the whole matched string
}

async function responseReplace(response) {
  // REPLACE WITH YOUR WORKER
  const thisWebsiteBase = "anime-rev-proxy.rynco.me/"

  const { headers } = response;
  const contentType = headers.get("content-type") || "";
  if (
    contentType.includes("application/json")
    || contentType.includes("application/text")
    || contentType.includes("text/html")
    || contentType.includes("application/xml")) {
    // do a search and replace for each value
    let text = await response.text();
    for (let key in reverseProxyBase) {
      const val = reverseProxyBase[key];
      text = text.replaceAll(val, thisWebsiteBase + key);
    }
    return new Response(text, response);
  } else {
    return response;
  }
}

export default {
  async fetch(request, env) {
    try {
      const url = new URL(request.url);
      const pathname = url.pathname

      const paths = pathname.split("/");
      if (paths.length <= 1) {
        return noSuchWebsite("<empty path>");
      }
      const reverseProxyWebsite = reverseProxyBase[paths[1]]
      if(!reverseProxyWebsite) {
        return noSuchWebsite(paths[1])
      }
      url.pathname = pathname.substring(paths[1].length+1)
      url.host = reverseProxyWebsite
      
      var res = await fetch(new Request(url.toString(), request));
      return await responseReplace(res);
    } catch(e) {
      return new Response(e.stack, { status: 500 })
    }
  }
}